Interaction of spatial solitons with a localized spatially-modulated medium

The propagation of solitons through spatially-modulated media is studied nu merically as a function of the amplitude, frequency and length of the spati al nonuniformities. It is shown that for a fixed amplitude and length of mo dulation, an increase in frequency may result in a soliton that propagates in the opposite direction to the one encountering the nonuniform medium bec ause of reflection, whereas, for a fixed frequency and length, an increase in the amplitude of the spatial modulation results in a surface wave and a soliton that may propagate towards either the right or left boundary. In ei ther case, the radiation increases as the amplitude of the spatial modulati on is increased. For fixed amplitude and frequency, an increase in the leng th of nonuniformities results in both surface waves whose amplitude decreas es and right-traveling solitons whose velocity decreases as the length of t hese nonuniformities is increased. A comparison between space and time Vari ations of the dispersion index is also presented. (C) 2001 IMACS. Published by Elsevier Science B.V. All rights reserved.